Effect of biochar on microbial composition and function in continuous cropping ginseng soil

Objective  To explore the changes of soil bacterial community diversity and function after planting ginseng (Panax ginseng C. A. Mey.), and the effects of biochar application on soil bacterial community diversity and function.

Method  The field experiments with different biomass charcoals were conducted to improve the soil of continuous cropping ginseng field, and the changes of bacterial community diversity and function were analyzed by high-throughput sequencing technology.

Result  The bacteria number of Spartobacteria_genera_incertae_sedis, Sphingomonas, Gemmatimonas,Afipia, Gp1, Gp2, Gp3, Gp6, and Rummeliibacillus in the soil after planting ginseng significantly decreased, indicating that cultivating ginseng or ginseng root secretions might inhibit the growth of these bacteria. In addition, the number of Gaiella bacteria in soil of planting ginseng field increased significantly, and further increased after applying biochar, indicating that all cultivating ginseng, ginseng root exudates and applying biochar could promote the growth of bacteria. Compared with the new forest soil, the number of soil bacteria, community diversity, bacterial taxonomic composition and the proportion of dominant genera in the continuous cropping ginseng field declined to varying degrees, and showed an increase in proportion of single dominant population. Biomass charcoal treatment had a certain positive regulation effect on the above-mentioned deterioration trend, and the change trend of bacterial classification and quantity tends to those of the new forest soil. The biomass charcoal assisted in improving bacteria chromatin structure and dynamics, transcription, replication recombination and repair, signal transduction mechanism and cell defense function.

Conclusion  Biochar application can improve soil bacterial diversty, regulate bacterial community structure and function, and make soil development of continuous cropping ginseng field in a good direction. The result provides therotical reference for soil restoration and ginseng cultivation in the continuous cropping ginseng field.